Android开发代码片段积累(一)

来源：互联网发布：linux函数 sleep 编辑：程序博客网时间：2024/05/16 19:03

本博客积累Android开发中常用的代码片段, 如果用到的话, 可以直接拿来用. 以后可以考虑将这些代码片段封装成组件或工具类. 不能保证代码片段没有bug, 在使用时需要经过测试.

1 切换系统中某个组件的状态,设置其enable或disable

public void toggleComponent(View view){        PackageManager pm = getPackageManager();        String pkgName = "com.aa.activitytest";        String comName = "com.aa.activitytest.SecondActivity";        ComponentName componentName = new ComponentName(pkgName, comName);        int state = pm.getComponentEnabledSetting(componentName);        boolean isEnable = state == PackageManager.COMPONENT_ENABLED_STATE_ENABLED                || state == PackageManager.COMPONENT_ENABLED_STATE_DEFAULT;        if(isEnable){            pm.setComponentEnabledSetting(componentName, PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);        }else {            pm.setComponentEnabledSetting(componentName, PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);        }    }

2 列出系统中所有安装的app的信息

        PackageManager pm = getPackageManager();        List<PackageInfo> packages = pm.getInstalledPackages(PackageManager.GET_UNINSTALLED_PACKAGES);                for(PackageInfo packageInfo : packages){                        //应用图标            Drawable icon = packageInfo.applicationInfo.loadIcon(pm);                        //标题            CharSequence lable = packageInfo.applicationInfo.loadLabel(pm);                        //包名            String packageName = packageInfo.packageName;                    }

3 将raw中的apk拷贝到/data/data/包名/files/中

//1 拷贝raw中的apk文件        InputStream in = null;        OutputStream out = null;        try {            in = getResources().openRawResource(R.raw.dex_apk);            out = this.openFileOutput("dex_apk.apk", Context.MODE_PRIVATE);            copyFile(in, out);        } catch (FileNotFoundException e) {            e.printStackTrace();        }finally {            try {                if (in != null) in.close();            }catch (IOException e){}            try{                if (out != null) out.close();            }catch (IOException e){}        }

4 拷贝文件

    private void copyFile(InputStream in, OutputStream out){        byte[] buffer = new byte[1024];        int len = 0;        try {            while((len = in.read(buffer) ) != -1){                out.write(buffer , 0 , len);            }        } catch (IOException e) {            e.printStackTrace();        }    }

5 使用DexClassLoader加载 /data/data/包名/files/ 下的apk的classes.dex ，并通过反射执行。

        //2 加载并执行apk中的类        String pkgDataPath = "/data/data/" + getPackageName();        String optimizedDirectory = pkgDataPath + "/files/";        String dexPath = optimizedDirectory + "dex_apk.apk";        DexClassLoader dexClassLoader = new DexClassLoader(dexPath, optimizedDirectory, null, this.getClassLoader());        try {            Class personClazz = dexClassLoader.loadClass("com.aa.dexapk.Person");            Object newInstance = personClazz.newInstance();            Method method = personClazz.getMethod("doWork");            method.invoke(newInstance);        } catch (Exception e) {            e.printStackTrace();        }

6 动态加载其他已经安装的apk的dex文件，并通过反射执行

private void useDexClassLoader(){            //创建一个意图，用来找到指定的apk            Intent intent = new Intent("com.suchangli.android.plugin", null);            //获得包管理器            PackageManager pm = getPackageManager();            List<ResolveInfo> resolveinfoes =  pm.queryIntentActivities(intent, 0);            //获得指定的activity的信息            ActivityInfo actInfo = resolveinfoes.get(0).activityInfo;                        //获得包名            String pacageName = actInfo.packageName;            //获得apk的目录或者jar的目录            String apkPath = actInfo.applicationInfo.sourceDir;            //dex解压后的目录,注意，这个用宿主程序的目录，android中只允许程序读取写自己            //目录下的文件            String dexOutputDir = getApplicationInfo().dataDir;                        //native代码的目录            String libPath = actInfo.applicationInfo.nativeLibraryDir;            //创建类加载器，把dex加载到虚拟机中            DexClassLoader calssLoader = new DexClassLoader(apkPath, dexOutputDir, libPath,                            this.getClass().getClassLoader());                        //利用反射调用插件包内的类的方法                        try {                        Class<?> clazz = calssLoader.loadClass(pacageName+".Plugin1");                                                Object obj = clazz.newInstance();                        Class[] param = new Class[2];                        param[0] = Integer.TYPE;                        param[1] = Integer.TYPE;                                                Method method = clazz.getMethod("function1", param);                                                Integer ret = (Integer)method.invoke(obj, 1,12);                                                Log.i("Host", "return result is " + ret);                                        } catch (ClassNotFoundException e) {                        e.printStackTrace();                } catch (InstantiationException e) {                        e.printStackTrace();                } catch (IllegalAccessException e) {                        e.printStackTrace();                } catch (NoSuchMethodException e) {                        e.printStackTrace();                } catch (IllegalArgumentException e) {                        e.printStackTrace();                } catch (InvocationTargetException e) {                        e.printStackTrace();                }    }

7 获取其他包中的资源（pm.getResourcesForApplication(pkgName) )

Intent intent = new Intent("com.suchangli.android.plugin", null);          //获得包管理器          PackageManager pm = getPackageManager();          List<ResolveInfo> resolveinfoes =  pm.queryIntentActivities(intent, 0);          //获得指定的activity的信息          ActivityInfo actInfo = resolveinfoes.get(0).activityInfo;                    //获得包名          String pacageName = actInfo.packageName;                     try {              Resources res = pm.getResourcesForApplication(pacageName);                            int id = 0;              id = res.getIdentifier("ic_launcher", "drawable", pacageName);              Log.i("", "resId is " + id);                                      } catch (NameNotFoundException e) {              e.printStackTrace();          }

8 Context.getDir创建并返回目录

Context.getDir（“mydir”）返回的目录的绝对路径是： /data/data/package_name/app_mydir 。

9 获取Activity的图标

    private Bitmap getIconForActivity(Context context, String packageName, String activityName){                ComponentName activityComp = new ComponentName(packageName, activityName);        PackageManager pm = context.getPackageManager();        Intent intentToResolve = new Intent();        intentToResolve.setComponent(activityComp);        ResolveInfo resolveInfo = pm.resolveActivity(intentToResolve, 0);        Drawable iconDrawable = resolveInfo.activityInfo.loadIcon(pm);        return Utilities.createIconBitmap( iconDrawable, context);    }

其中Utilities为Launcher中的工具类。

10 获取当前app的签名信息：

/** * get signature of current package * @param context * @return signature, null if there is no signature */public static String getSignature(Context context){    Log.i(TAG, "SignatureUtils.getSignature");    PackageManager pm = context.getPackageManager();    String pkgName = context.getPackageName();    try {        PackageInfo pi = pm.getPackageInfo(pkgName, PackageManager.GET_SIGNATURES);        Signature[] signatures = pi.signatures;        if(signatures != null && signatures.length > 0){            String signature =  signatures[0].toCharsString();            Log.i(TAG, "Signature of current package is : " + signature);            return  signature;        }    } catch (PackageManager.NameNotFoundException e1) {        e1.printStackTrace();    }    return null;}

11 获取apk文件的签名信息（未安装，只是一个apk文件）

/** * get signature of an apk file * this method will execute quit a long time, so it is suitable to call it in sub thread * @param context * @param apkFilePath * @return signature , null if there is no signature , or apkFilePath is wrong */public static String getSignatureOfApk(Context context, String apkFilePath){    Log.i(TAG, "SignatureUtils.getSignatureOfApk");    if (TextUtils.isEmpty(apkFilePath)) return null;    PackageManager pm = context.getPackageManager();    PackageInfo pi = pm.getPackageArchiveInfo(apkFilePath, PackageManager.GET_SIGNATURES);    Signature[] signatures = pi.signatures;    if(signatures != null && signatures.length > 0){        String signature =  signatures[0].toCharsString();        Log.i(TAG, "Signature of " + apkFilePath + " is : " + signature);        return  signature;    }    return null;}

12 获取apk文件的权限信息

   public static List<PermissionInfo> getApkPermissions(String apkFile, PackageManager pm){        if(DEBUG) Log.i(TAG, "PackageUtils.getApkPermissions");        List<PermissionInfo> permissionInfos = new ArrayList<PermissionInfo>();        PackageInfo packageInfo =  pm.getPackageArchiveInfo(apkFile, PackageManager.GET_PERMISSIONS);        String[] permissions = packageInfo.requestedPermissions;        for(String permName : permissions ){            try {                PermissionInfo permissionInfo = pm.getPermissionInfo(permName, 0);                permissionInfos.add(permissionInfo);            } catch (PackageManager.NameNotFoundException e) {                e.printStackTrace();            }        }        return permissionInfos;    }

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